Summary Advancements in device miniaturization, integrated circuits packaging, microfabrication technologies, and biocompatible materials have made possible the development of complex neural prostheses designed to restore lost functions such as movement, hearing or vision. Neurological diseases result in significant impairment for millions of individuals worldwide. The requirements for these advanced neural interfaces are not met by currently approved implant devices, which use rigid packaging and are equipped with mostly single or low-density multielectrodes for sensing of physiological events or delivery of electrical stimulation. Neural prostheses such as retinal prostheses require a large number of electrodes, due to the amount of information that must be conveyed, and cannot rely on existing technology. To interface effectively with the nervous system and to open up new applications, miniaturized, flexible electrodes and packaging are needed. As continuation of an on-going Phase II SBIR grant entitled "Insulating Coatings for Implant Devices and Ribbon Cables" funded by the National Institute of Neurological Disorder and Stroke, we propose long term in-vitro and in-vivo studies for our flexible neural interfaces to collect a comprehensive set of data in preparation of clinical trials and regulatory approval. The retinal implant was chosen as test vehicle for our technology because of the complexity of the device with a large number of channels, the harsh environment for our encapsulation technology and the delicate nature of the tissue. However, the technology we develop will be easily applicable to other devices. We will develop novel, 3-dimensional wide field microelectrode arrays to improve contact to the retina and reduce damage to the tissue. Additionally, these electrode arrays will have a 10-mm diameter area of contact with the retina, thus enabling a wide field of vision. To enable testing of full system implants in vivo in dogs our interfaces will be connected to a proven hermetically sealed implantable stimulator electronics package from Second Sight. This is a key feature of this proposal made possible by our alliance with Second Sight. Years of development have gone into the microelectronics and materials for this next generation implant, and we will be able to leverage that development for this proposal. Advancements in microfabrication and materials have made possible the development of flexible neural interfaces. These medical devices are targeted at treating incurable neurological disorders and solve difficult technical problems that are limiting the capability of neural implant devices. Such diseases are widespread in the population as a whole and their impact on individual health is profound. The progress made by us so far with support from NINDS through Phase II SBIR demonstrates that our technology has the potential to lead to a successful commercialization of complex and challenging neural interfaces like the retinal stimulator and make a real impact on public health by increasing the capability of implantable neural prostheses. [unreadable] [unreadable] [unreadable]